io.c: recycle garbage on write

* string.c (STR_IS_SHARED_M): new flag to mark shared mulitple times
  (STR_SET_SHARED): set STR_IS_SHARED_M
  (rb_str_tmp_frozen_acquire, rb_str_tmp_frozen_release): new functions
  (str_new_frozen): set/unset STR_IS_SHARED_M as appropriate
* internal.h: declare new functions
* io.c (fwrite_arg, fwrite_do, fwrite_end): new
  (io_fwrite): use new functions

Introduce rb_str_tmp_frozen_acquire and rb_str_tmp_frozen_release
to manage a hidden, frozen string.  Reuse one bit of the embed
length for shared strings as STR_IS_SHARED_M to indicate a string
has been shared multiple times.  In the common case, the string
is only shared once so the object slot can be reclaimed immediately.

minimum results in each 3 measurements. (time and size)

Execution time (sec)
name                            trunk   built
io_copy_stream_write            0.682   0.254
io_copy_stream_write_socket     1.225   0.751

Speedup ratio: compare with the result of `trunk' (greater is better)
name    built
io_copy_stream_write            2.680
io_copy_stream_write_socket     1.630

Memory usage (last size) (B)
name                            trunk           built
io_copy_stream_write            95436800.000    6512640.000
io_copy_stream_write_socket     117628928.000   7127040.000

Memory consuming ratio (size) with the result of `trunk' (greater is better)
name    built
io_copy_stream_write            14.654
io_copy_stream_write_socket     16.505

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57469 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 36 insertions, 4 deletions

diff --git a/io.c b/io.c
index 322aabedc5..d03519be92 100644
--- a/io.c
+++ b/io.c
@@ -1419,10 +1419,40 @@ do_writeconv(VALUE str, rb_io_t *fptr, int *converted)
     return str;
 }
 
+struct fwrite_arg {
+    VALUE orig;
+    VALUE tmp;
+    rb_io_t *fptr;
+    int nosync;
+};
+
+static VALUE
+fwrite_do(VALUE arg)
+{
+    struct fwrite_arg *fa = (struct fwrite_arg *)arg;
+    const char *ptr;
+    long len;
+
+    RSTRING_GETMEM(fa->tmp, ptr, len);
+
+    return (VALUE)io_binwrite(fa->tmp, ptr, len, fa->fptr, fa->nosync);
+}
+
+static VALUE
+fwrite_end(VALUE arg)
+{
+    struct fwrite_arg *fa = (struct fwrite_arg *)arg;
+
+    rb_str_tmp_frozen_release(fa->orig, fa->tmp);
+
+    return Qfalse;
+}
+
 static long
 io_fwrite(VALUE str, rb_io_t *fptr, int nosync)
 {
     int converted = 0;
+    struct fwrite_arg fa;
 #ifdef _WIN32
     if (fptr->mode & FMODE_TTY) {
 	long len = rb_w32_write_console(str, fptr->fd);
@@ -1432,11 +1462,13 @@ io_fwrite(VALUE str, rb_io_t *fptr, int nosync)
     str = do_writeconv(str, fptr, &converted);
     if (converted)
 	OBJ_FREEZE(str);
-    else
-	str = rb_str_new_frozen(str);
 
-    return io_binwrite(str, RSTRING_PTR(str), RSTRING_LEN(str),
-		       fptr, nosync);
+    fa.orig = str;
+    fa.tmp = rb_str_tmp_frozen_acquire(str);
+    fa.fptr = fptr;
+    fa.nosync = nosync;
+
+    return (long)rb_ensure(fwrite_do, (VALUE)&fa, fwrite_end, (VALUE)&fa);
 }
 
 ssize_t